1. Field of the Invention
The present invention relates to a limited slip differential gear assembly for use in a driving system for vehicles and the like.
2. Description of the Prior Art
Generally, a limited slip differential gear assembly used in a vehicle is prepared to handle the occurrence of slippage or skidding of one tire by providing a sufficient rotation force to the other tire which is not experiencing slippage. For example, such a limited slip differential gear assembly is disclosed in Japanese Laid-Open Patent Publication No.(Kokai)49(1974)-104828.
The differential gear assembly disclosed in the above-referenced publication comprises: a case for receiving rotational input power to rotate with respect to a rotational axis; a pair of side gears aligned in the case coaxially with the rotational axis; and a few pairs of elongated pinion gears arranged in parallel to the rotational axis. Each pinion gear has gear teeth with circumferential surfaces and is received in a cylindrical bore so as to movably supported by the cylindrical bore surface. Two cylindrical bores for the paired pinion gears overlap each other so that the half portions of the paired pinion gears at the central portion of the case can be engaged with each or,her. Moreover, the other half portion of one pinion gear of the pair is engaged with one of the side gears at one end portion of the case, and that of the other pinion gear is engaged with the other side gear at the opposite end portion of the case. Each of the side gears is connected with each of the drive shafts, or the left and right axles connected to the wheels of the vehicle, respectively.
In the above conventional gear assembly, each of the pinion gears being rotatably supported on the bore surfaces and movable in the cylindrical bores is axially positioned at both ends thereof. Specifically, one end of the pinion gear at the central side abuts a flat terminal surface of the cylindrical bore, and the other end which extends to the end of the side gear is stopped by a flat side wall which is fixed to the opening of the cylindrical bore by a snap ring to close the cylindrical bore.
According to the above structure, in order for the axes of the pinion gears to be stably positioned, the pinion gears are not supported very tightly. Consequently, the pinion gears tend to move easily and incline. Moreover, the cylindrical bores are completely closed by the side walls, making it impossible to supply additional lubricant to the pinion gears. As a result, lubrication of the pinion gears deteriorates over time, thus giving rise to a progressive in decrease in the durability of the pinion gears.